The present invention relates to an improved lubricating mechanism for a slide bearing.
Japanese Patent Unexamined Publication No. 54-140044 discloses a self-lubricating slide bearing which has a cylindrical sleeve made of an oil-containing sintered alloy and a perforated cylindrical bearing metal member made of a rolled alloy and tightly fitted in the sleeve of the sintered alloy. During operation, lubricating oil contained in the sintered alloy is thermally expanded to exude through the perforations of the bearing metal member so as to form an oil film between the surface of the bearing metal member and a shaft on this member.
Japanese Patent Unexamined Publication No. 54-159544 discloses another type of self-lubricating bearing in which inner peripheral portion of the sintered alloy is partially sized to reduce the rate of permeation of the oil, so as to enable the lubricating oil to be circulated in the direction of the pressure difference.
The self-lubricating slide bearing disclosed in Japanese Patent Unexamined Publication No. 54-140044, however, is not arranged to enable an oil film to be formed and maintained between the shaft and the bearing metal member in a manner to correspond to the speed of rotation of the rotary shaft. Therefore, this known self-lubricating slide bearing could not satisfactorily operate as a high-speed bearing, and troubles such as shortage of lubricating oil has been often encountered.
On the other hand, in the other type of known self-lubricating slide bearing, the shaft is supported in a floating manner by the film of lubricating oil. However, since the oil film is not formed by a dynamic pressure, the lubricating function is insufficient for enabling the bearing to be used as a high-speed slide bearing.